Kurzweil Forte - Manual (Page 101)

Program Edit Mode
VAST and KB3 Programs
7-4
VAST and KB3 Programs
It is important to understand the difference between VAST programs and KB3 programs.
VAST programs contain up to 32 layers, each of which contains a keymap or KVA oscillator.
Keymaps consists of a number of samples assigned to a particular keyboard range. KVA
oscillators use powerful DSP (digital signal processors) to generate a range of simple and
complex waveforms. See Editing VAST Programs With KVA Oscillators for more details. See
VAST Program Structure below for details on VAST programs.
KB3 programs use a much different architecture. There are no layers or algorithms, just
a set of oscillators (designed to emulate the tonewheels in a Hammond Organ) that start
running as soon as you select a KB3 program. See KB3 Program Structure for details on KB3
programs.
VAST Program Structure
“Figure 7-1 VAST Program Structure” on page 7-5 depicts the hierarchy of a VAST
program, from individual samples all the way up to Multis, which can contain up to 16
programs.
Every VAST program contains at least one layer. A layer consists of a keymap and an
algorithm for processing the samples contained in the keymap. Each sample is a separate
digital recording of some kind of sound: musical, vocal, industrial, any sound at all.
Individual samples are assigned to specific key ranges (from A 2 to D 3, for example), and
are also assigned to be triggered at specific attack velocities. These assignments constitute the
keymap.
When you trigger a note, the Forte looks to the keymap of each layer of the currently active
VAST program(s) to determine which samples to play. The sound engine then fetches the
requested samples and generates a digital signal representing the sound of the samples. This
signal first passes through the DSP functions that make up the algorithm. It then passes
through the Forte’s effects processor, and finally appears—with some level of effects applied
to it—at one or more of the audio outputs.
The layer is the VAST program’s basic unit of polyphony, that is, each layer constitutes one of
the 128 voice channels the Forte can activate at any time. If you have a program that consists
of two layers covering the note range from A 0 to C 8, each key you strike triggers two voice
channels.